﻿#include <iostream>
#include <vector>
using namespace std;
int main(){
    int a = 5;
    float b = 3.2f;
    decltype(a + b) result = a + b; // result 是 float
    // 应用场景举例子
    vector<int> vec{1, 2, 3, 4, 5};
    decltype(vec.size()) count = 0; // count 是 size_t
}